The present invention relates to a method by which a fluid mixture containing a plurality of components is chromatographically separated into three or more fractions enriched in the respective components.
Chromatographic separation techniques employing solid adsorbents are extensively used in industrial applications. Among the processes currently in commercial use are a continuous chromatographic separation method that employs a simulated moving-bed system as described in Japanese Patent Publication No. 15681/1967, whose U.S. equivalent is U.S. Pat. No. 2.985,589, and semi-continuous chromatographic separation methods as described in Japanese Patent Publication No. 37008/1981, whose U.S. equivalent is U.S. Pat. No. 4,332,623, and Japanese Patent Publication No. 55162/1985, whose U.S. equivalent is U.S. Pat. No. 4,267,054. These methods of chromatographic separation have met with some commercial success, but they are basically designed for separating mixture of components into two fractions. Great difficulty has been encountered in achieving separation into three or more fractions using these methods.
A simulated moving-bed system requires a minimum of four packed beds. The semi-continuous chromatographic separation method disclosed in Unexamined Published Japanese Patent Application No. 37008/1981 requires three or four packed beds, and the equipment it employs is complicated and expensive.
Further, a method of separation into components A and B has been known in USP 4,267,054 (Japanese Patent Publication No. Sho-60-55162). The USP discloses a method for the chromatographic separation of each of the soluble components of a feed solution containing as major components (1) a component A which is relatively less adsorbed by a solid adsorbent having ion-exchanging or molecular sieve action and (2) a component B which is more selectively adsorbed by the solid adsorbent having ion-exchanging or molecular sieve action, the solid adsorbent having its adsorbency restored by displacing selectively adsorbed components.
However, the above-mentioned method is achieved by only chromatographic separation of the components A and B.